We will develop and test a simulator of diagnostic vascular ultrasound for use in medical education and professional certification. The simulator will include not only two-dimensional (2D) images but also Doppler spectral waveforms to simulate duplex ultrasound scanning. The rationale is that education in diagnostic ultrasound has traditionally been based on an extended duration of clinical exposure during training, with a relatively large number of procedures performed and interpreted under the supervision of a qualified faculty member. However, this apprenticeship approach to training is rapidly becoming untenable due to inadequate patient exposure and limited faculty teaching time. Simulation has the potential to address these needs. The proposed project builds on the results of our previous research for NIH, in which we developed an image- based computer modeling technique for simulating blood flow in dialysis access sites. This project also builds on the results of our previous research in which we developed a simulator for training and competency testing in cardiac ultrasound. In this simulator, manipulation of a mock transducer on a mannequin produces the appropriate 2D ultrasound image on a computer monitor. The skill of the trainee is tested in terms of the anatomic location of the images acquired and the ability of the trainee to make the correct diagnosis. The Specific Aims of the project are as follows: Specific Aim #1: We will develop a Doppler simulator able to reproduce the key components of a clinical Doppler ultrasound examination. The Doppler waveforms will be derived from 3D computational modeling of blood flow, which was developed by our collaborators at the University of Washington. Specific Aim #2: We will verify the accuracy of the simulation by comparing blood flow velocity measured from the simulator waveforms with the true velocities in the 3D models. Specifc Aim #3: To enhance simulator realism we will generate 2D color Doppler images. The health care benefit of this project will be enhanced patient safety through reduction of medical errors due to misdiagnosis, based on improved training of medical professionals and skill-based competency testing. Health care costs will be reduced because clinic resources can be devoted to patient care until trainees master basic ultrasound skills. In Phase II we plan to expand our library of vascular cases and use these data sets to assess the validity of competency testing using our Doppler simulator. Three types of validation will be performed in Phase II: 1) training efficacy will be evaluated by repeating a test before and after training with the simulator, 2) construct validity will be assessed by comparing experts vs. novices to demonstrate that their test results differ appropriately, and 3) reliability will be measured in terms of test-retest correlation.